1. Field of the Invention
The present invention relates to a damper assembly with a torque limiter which is provided between an engine and a transmission so as to protect a damper against an excess load.
2. Related Background Art
A damper assembly drives a driven member from a driving member directly coupled to an engine through a torsion spring. With the configuration, the torsion spring adheres to an overload generated by a combustion of an engine. As a result, the spring is possibly fatigued or damaged. Therefore, the damper assembly has conventionally been provided with an engagement portion in a predetermined position of each member of a driving member, a driven member driven through a torsion spring, an intermediate for separating a torsion spring, etc. so that the relative rotation between the members can be limited, and the torsion spring can be successfully protected against an excess load.
FIG. 4 is a front view showing each component of a prior damper assembly 10 as appropriately exploded. FIG. 5 is a sectional view along V-V shown in FIG. 4. FIG. 6 is a front view showing the maximum state of operation similar to FIG. 1. In the drawings, reference numeral 1 denotes a front cover; 2 denotes a rear cover; and 3 denotes a drive plate directly coupled to the output axis (shaft) of an engine. The drive plate 3 corresponds to the driving member of a damper. Reference numeral 5 denotes a retainer plate for receiving a torsion spring 80 for the drive plate 3; and 7 denotes a hub fixed to the retainer plate with a rivet 11. The combination of the retainer plate 5 and the hub 7 corresponds to the driven member.
Reference numeral 6 denotes a divider ring for dividing the torsion spring 80, and is attached around a outer periphery of the hub 7 for predetermined relative movement. Reference numeral 31 denotes a spring space of the drive plate 3; 32 denotes a shoulder portion formed in a predetermined position; 33 denotes a spring receiver; and 51 denotes a spring receiver of the retainer plate 5 for cooperation with the spring receiver 33 of the drive plate 3 to perform a pressing operation through the torsion spring 80.
The torsion spring 80 is divided by a projecting portion 61 of the divider ring 6. In the example, shown in the drawings, there are three sets of torsion springs 80 between the drive plate 3 and the retainer plate 5. However, since they are divided by the divider ring 6, it is assumed that there are 6 sets of torsion springs 80 in total. In the example shown in the attached drawings, the torsion spring 80 includes three springs, that is, an outermost spring 81, a central spring 82, and a innermost spring 83. The divider ring 6 corresponds to the intermediate member. In the drawings, reference numeral 21 denotes a rivet hole; 22 denotes a positioning hole; and 23 denotes a weld portion.
By dividing the torsion spring 80, the length of the spring can be shortened, and the spring can be arranged along the circumference as shown in the attached drawings although each set of the springs is a linear spring, thereby attaining smooth and accurate operations of the springs.
In the attached drawings, the device is designed to rotate in the arrow R (counterclockwise) direction. When the drive plate 3 rotates with the output of the engine, the retainer plate 5 and the hub 7 fixed thereto are driven through the torsion spring 80 and the divider ring 6, and power is obtained from the output axis attached through a spline 73 of the hub 7.
The front cover 1 and the rear cover 2 are fixed to the drive plate 3, which is a driving member, with the weld portion 23, etc., and a retainer cover plate 4 is fixed to the retainer plate 5, thereby realizing effective seal with space formed therein. A viscous medium such as grease, oil, etc. is filled inside as a lubricant so that the viscous damping resistance can be allowed for the relative movement among the intermediate members such as a torsion spring, the divider ring 6, etc. and the driven member such as the retainer plate 5, etc., thereby suppressing the generation of wear and noise.
When a load on the damper assembly becomes large, the shoulder portion 32 of the drive plate 3 is engaged with a shoulder portion 62 provided in the projecting portion 61 of the divider ring 6 as shown in FIG. 6, and a shoulder portion 64 formed in an inner projecting portion 63 of the divider ring 6 is engaged with a shoulder portion 72 formed in a projecting portion 71 of the hub 7, thereby preventing the torsion spring 80 from closely adhering.
Recently, there is an increasing demand for a smaller device to be mounted in a smaller space with larger output engine. Therefore, the damper necessarily happens to be subject to excess torque, thereby causing a heavy damage. Therefore, it is an object of the present invention is to provide a damper assembly with torque limiter with a proper means for protecting the damper against excess torque.